1. Field of the Invention
The present invention relates to a method for producing curved slide fasteners which are used as sewed on bags, children bags, pocket portions of cloths, etc. and also to a method for producing curved slide fastener chains used as preparatory products for the former.
2. Description of the Prior Art
Heretofore, in the production of curved slide fasteners, in the case of metallic fasteners it has been practiced that a pitch (interval) between the respective fastener elements planted on one side edge of one fastener tape is chosen large, while a pitch of the respective fastener elements planted on one side edge of the other fastener tape is chosen small, and thereby a curved inter-engaged portion is formed by the difference of pitches (for instance, see Laid-Open Japanese Patent Specification No. 59-103607 (1984)). Also, in the case of coil fasteners it has been practiced to form a curved configuration by heating with a heater. Furthermore, as methods other than the above-described method, a method of cutting slits in a fastener tape portion and then sewing it on cloths or a method of using left and right fastener tapes having different widths has been practiced.
However, in the case of the above-described .method of forming a curved inter-engaged portion by the difference of pitches, the production was complicated and expensive in cost, and the methods of making use of a heater, cutting slits in the fastener tape portion, and using left and right fastener tapes having different widths, involved probelms such that generally it was difficult to shape into a desired curved configuration and sewing thereof was troublesome.